Gases are sold and shipped in metal tanks under high pressure. A tank of compressed air has a volume of $26\mathrm{.}0L$ and is pressurized from $1$atm to $18\mathrm{.}6$atm at $T=298K.$ What work $($in $kJ)$ had to be done in filling this tank if the compressor operates at $18\mathrm{.}6$ atm? $($Hint: What volume did the air occupy before it was compressed?$)$

$kJ$